Lect 11 - CNS (Cranial Meninges and Circulation)

Question 1

What is the Dura Mater

Answer 1

The outer layer of The Cranial Meninges

Question 2

What are the two layers of the Dura Mater

Answer 2

Periosteal Cranial Dura (Outer)

Meaningeal Cranial Dura (Inner)

Question 3

The space between the two Dura Mater layers contains?

Answer 3

Dural Sinuses (Large Veins)

Question 4

In the Dura Mater what do the Dural Septae separate and form

Answer 4

Falx Cerebri
Tentorium Cerebelli
Falx Cerebelli
Diaphragma Sellae

Question 5

What is the Falx Cerebri? What does it contain?

Answer 5

A meningeal layer that covers the brain, extends into the longitudinal fissure

Superior Sagittal Sinus
Inferior Sagittal Sinu

Question 6

The anterior portion of the Falx cerebri attaches to

Answer 6

Crista Galli

Question 7

The posterior portion of the Falx cerebri attaches to

Answer 7

Tentorium cerebelli

Question 8

What is the Tentorium Cerebelli

Answer 8

Separates cerebellar hemisphere with cerebral hemisphere
Occipital lobe of cerebrum and cerebellum
are separated

Contains Transverse Sinus

Question 9

What is the Falx Cerebelli

Answer 9

Contains the Occipital Sinu
Separates the Cerebellar Hemispheres

Question 10

What is the Diaphragma Sellae

Answer 10

Anchors Dura Mater to Sphenoid Bone
Encases Pituitary Gland (Separates it from the bone)

Question 11

What are Dural Venous Sinuses

Answer 11

Channels in between Dura Mater layers

Act like veins
Contains blood
Receive some CSF

Question 12

Examples of Dural Venous Sinuses

Answer 12

Superior Sagittal Sinus
Inferior Sagittal Sinus
Transverse Sinus

Question 13

Superior Sagittal Sinus

Answer 13

Superior Border of Falx Cerebri

Question 14

Inferior Sagittal Sinus

Answer 14

Inferior Border of Falx Cerebri

Question 15

Transverse Sinus

Answer 15

Courses laterally with the tentorium cerebelli

Question 16

What is the Arachnoid Mater

Answer 16

The middle layer of The Cranial Meninges

Question 17

What does the Arachnoid Mater contain

Answer 17

Arachnoid Granulations
Subdural Space
Subarachnoid Space
Trabeculae

Question 18

Arachnoid Mater (Arachnoid Granulations)

Answer 18

Villi of the Arachnoid Mater

Cerebral Spinal Fluid can flow into these to enter venous circulation

Question 19

Arachnoid Mater (Subdural Space)

Answer 19

The space between the arachnoid mater and meningeal cranial dura

Question 20

Arachnoid Mater (Subarachnoid Space)

Answer 20

Space deep to the arachnoid mater

Question 21

Arachnoid Mater (Traberculae)

Answer 21

Collagenous Fibers, Weblike material that underlines the arachnoid layer

Anchor cerebral blood vessels

Question 22

What is the Pia Mater

Answer 22

Inner Cranial Meninges Layer

Attached to the surface of the brain
Anchored by astrocytes
Anchors large blood vessels of the cerebrum

Question 23

How does the blood brain barrier work?

Answer 23

Endothelial cells that are connected by tight junctions prevent the passage of water soluble material

Question 24

What can pass the blood brain barrier

Answer 24

Lipid-Soluble Material can pass from blood to cells in the brain/spinal cord

Water-Soluble can only pass through specific transport mechanisms

Question 25

What four regions is the BBB different than the rest of the brain

Answer 25

Hypothalamus Pineal Gland Capillaries Choroid Plexus Capillaries Pituitary Gland Capillaries

Question 26

What makes the Hypothalamus different (BBB)

Answer 26

Increased permeability for diffusion of hormones

Question 27

What makes the Pineal Gland Capillaries different (BBB)

Answer 27

Very permeable for pineal secretions

Question 28

What makes the Choroid Plexus Capillaries different (BBB)

Answer 28

No tight junctions Ependymal Cells form blood-CSF barrier By producing Cerebrospinal Fluid

Question 29

What makes the Pituitary Gland Capillaries different (BBB)

Answer 29

Permeable for hormone release

Question 30

What larger molecules do neurons need? How does it enter the brain?

Answer 30

Glucose, endothelial cells of BBB will constantly transport glucose from the blood to neurons (Blood concentration does not matter)

Question 31

Brain and Glycine

Answer 31

Glycine needs to be low in the brain, allowing for active transport to blood

Question 32

Cerebrospinal Fluid Function

Answer 32

Prevents neural tissue from touching bone Provides support for brain (Cushion) Transport nutrients to CNS Transport waste away from CNS

Question 33

CSF Appearance and Content

Answer 33

Colourless Plasma Few cells and low protein content

Question 34

How is CSF formed

Answer 34

Ependymal Cells of the Choroid Plexus produce CSF by removing water from blood and releasing it as CSF

Question 35

Ependymal Cells

Answer 35

Directly transports nutrients into CNS Directly transports waste away from CNS Produces Cerebrospinal Fluid

Question 36

Choroid Plexus

Answer 36

Contains Ependymal Cells which produces CSF and controls CSF function

Question 37

What is the pathway of CSF

Answer 37

CSF is produced in Choroid Plexus of the Lateral Ventricle --> Flows through interventricular foramen --> Flows into the third ventricle --> Flows into cerebral aqueduct of the midbrain --> Flows into the fourth ventricle --> Through the Lateral Aperture and Median Aperture

Question 38

Where does CSF end up

Answer 38

Most flows into subarachnoid space --> a small amount enters the central canal of the spinal cord Flows around the brain and spinal cord --> eventually enters arachnoid granulations --> ending up in circulation

Question 39

What structures have Choroid Plexus

Answer 39

All ventricles have them Most specifically roof of 3rd and 4th ventricle

Question 40

Why are neurons dependent on delivery

Answer 40

High energy demanding BUT do not have any energy reserves (No myoglobin) If blood supply is interrupted irreversible damage can occur As such blood vessels (specifically gray matter) are arranged in a dense meshwork